Process for preparing improved lubricating oils by acid treating then hydrofinishing the lubricating oils



llnited States Patent lice PROCESS FOR CATING OILS BY ACID TREATING THEN HY- DROFINISHING THEv LUBRICATING OILS Mam e K.- w s, on rim and B. Watson, Park Forest, 11L, assignmto Sinclair Corie puny, New York, N.-Y., a corporation of mine No Drawing. Filed Feb. 25 1951,. so. No. stress 1 Claim. (Cl. 208-264) 7 Our invention relates to a method for the manufacture of lubricating oil firacfions of improved properties from naphthenic base crude oils.

Patented July 5, 1960 SSU/100- F. oil and 6000 SSU/ 100 F. oil. After the acid treatment has been carried out, the sludge is removed from. the oil and the oil. is then neutralized with a conventional neutralizing. agent, such. as aqueous. soda. ash or aqueous caustic soda, After the aqueous solution of the neutralizing agent has been permitted to settle Normal processing techniques employed in the production oi lubricating oil fractions from naphthenio base crude oils involve vacuum distillation toproduce a raw lube distillate fraction, acid treatment of that iraction to remove undesirable aromatic acid-type sludge forrning constituents and an earth treatment. By this means there have been produced lubricating oils which are useful in formulating cutting oils, in railroad diesel engine lubricants, and for other purposes.

It is desirable that high quality lubricating oils have good color and color stability and at the same time be highly stable towards oxidation. In accordance with our invention, We have devised a process whereby lubricating oil fractions of improved properties from the standpoints of odor, color stability and resistance to oxidation can be manufactured from naphthenic base crude oils. At the 1 same time, the lubricating oils made when our process is carried out are not impaired irons the standpoint of solubility characteristics, that is, the ability of the oils to dissolve additives and dissolve such sludge-forming macrude oil to produce a distillate fraction, acid treating that distillate traction in a particular way, neutralizing the acid treated fraction, washing it with water until free of sulfonates and then subjecting the oil to the mild hydrogenation treatment. Thus, the first step in our process involves subjecting naphthenic base crude oil, preferably a light reduced crude oil, to steam or vacuum distillation to remove low boiling components and asphalt bottoms and at the same time produce one or more raw lube distillate fractions having a SSU viscosity at 100 F. of from to 6000 seconds. The lighter grades of distillate, after further refining as described below, are useful as base oils for cutting oils, rubber processing oils and othei industry lubricants, and the heavier grades, after further refining as described below, are useful as base oils for railroad diesel engine lubricants.

The second step in our process involves treating the raw lube fraction with sulfuric acid which is of 93 to 98 percent by weight strength. Where the raw lube fraction has a SSU viscosity at 100 F. of 50 seconds, the amount of sulfuric acid employed is within the range from 5 to 10 pounds of acid per barrel of oil. On the out, the oil. is then washed with. water until. free of sulfonates (.zero ash)- The. oil is then ready for the subsequent mild hydrogenation step.- Acid treatment is essential to our process because other known processes for refining raw lubricant fractions, such as solvent ex firaction with furfural or phenol, lack the selectivity required for obtaining maximum oxidation stability to-- gether with high solubility characteristics.

The final step of our process consists of .a mild hydrogenation employing a cobalt supported on alumina catalyst. Various methods for manufacturing such catalysts have been described in the art, such as in Byrns Patent 2,325,033, and the catalysts generally consist essentially of from about 2-to 5 percent by weight of cobalt oxide and from about 5 to 15 (percent by weight of molybdic oxide, the balance being alumina. Suitable catalysts can also be prepared as described in Teter et al. application Serial No. 514,693, filed June 10, 1955. In the hydrogenation operation, a temperature of from 450 to 700' E, a pressure of from 400 to 700 p.s.-i.g. and a weight hourly space velocity (weight units of oil per weight unit of catalyst per hour) of from 5 to,20 are used. The oil is hydrogenated while it is in admixture with from 500 to,2000 standard cubic feet of hydrogen per barrel of oil,- and the operation is carried out in such manner that the hydrogen consumption amounts to from 5 to 30 standard cubic feet of hydrogen per barrel of oil feed. This mild hydrogenation has a decided'economic advantage over the conventional earth finishing processes, and in addition it results in higher yields by eliminating earth adsorption loss andan improved odor, color, color stability, and oxidation stability of the finished oil.

A specific example which illustrates our process is as follows: V

A Gulf Coast naphthenic light reduced crude obtained by atmospheric distillation of a whole naphthenic crude over caustic to neutralizeorganic acids inherent in the crude was charged to a vacuum distillation unit for further separation by distillation. The light reduced crude fraction was 42.6 percent by volume on the whole crude, and upon vacuum distillation several fractions were taken oiT near the tower top as lightluberdistillates, a fraction ofi near the tower middle as a medium lube distillate, a lower side-stream as a heavy lube distillate, with the tower bottoms being heavy reduced crude. The medium lube distillate which is a 17.5% heart cut fraction (on light reduced crude) was the specific starting material for this example. This material had the following physical tests: 19.3 API gravity, 440 F. flash .point, 1972 SSU at F. viscosity, 89.5 SSU at 210 F. viscosity, 11

Hydrogen to Oil'R o, .[b 1,500 Catalyst Used Cobalt Molybdate on r Alumina Hydrogen Consumption, s.c.i./b 12 Earth Used.-

viscosity index, F. pour point, 138.5 specific dispersion,

. and 6-, NPA color.

This medium lube distillatewas then subjected to acid treatment toremove undesirable aromatic type sludge forming constituents, thereby efifecting improvements in such properties .as color and oxidation stability. This acid treatment was performed as a continuous process 0' using 37 pounds of 98 percent sulfuric acid per barrel of charge stock' andtreatment at a temperature of 140 F. 7 Acid sludge precipitation'was aided by electrode sludge precipitators. After the sludge had been removed from the oil, the acid oil was then neutralized with a soda ash 'fsolution; heated to 180 F. -to allow 'settling'out of the spent soda solution and soaps, and given .a hot water spray wash until the oil was ,free of sulfona-tes. The water 7 Physical properties of charge stock to finishing process. .213

' Refractive index (N 1.5084

hour at 350 in rotating oven. 7

Normal finishing operations for treating such naphthenic oils' consist of earthclay contact or percolation adsorptive techniques. The method of finishing employed in accordance with our invention difiers from the normal finishing techniques in that in. accordance with our invention a mild hydrogenation procedure is utilized. The improvement produced when our process is employed f is shown by the'information given below, in which a portion ofthe oil processed as described Was-finished by portion was'finished by earth contacting. The'hydrofinishing and earth contacting were performed in accordance with the following processing conditions:

Earth Hydroflnishlng Percolation Temperature, F

650 V 160. Pressure, p.s.1.g WHSV Product Yield, gVolume Percent.-- 100--;, 99.1. j

' 1 7 Floridin Neutral Clay. 200.

Earth Dosage, Bbls/Ton weight Hourly Space Velocity (pounds of charge 011 per pound of catalyst per hour).

Analyzed approximately 3% cobalt oxide sndlO percent molybdic oxide by weight, the remainder being alumina.

A comparison of the products, after light steam stripping of the;hydrofinished oil to remove dissolved Hydro- Earth finished Finished 7 Product 'Product Gravity, APT 2l.5 21.3. Flash, F .440 445. Fire, F V 510 510. Viscosity, SUS at 210 F p I 75.7 76.6. Viscosity, SUS at 100 F 1,260 1,300 Viscosity Index; 23.7 23.0. Pour, F- 5. Color, N PA--- 3- 326-. Color Stability (NPA) 3- to 4 3 2; to

Specific Dispersion f 1315-.."--. 132.8, Iodine Nn 18.3 19.5. Sulfur, Perce 0.16-. 0.l7. Refractive Index (Nn 1.5080 1.5083 Odor Very Good Fair;

The improved oxidation resistance of the hydrofin-ished oil ,is showniby the following test results;

011 Oxidation Tests 1 After 144 ast Hours): s j- I Viscosity Rise, s s at 100 310 L118 Naphtha Insolubles, Percent-.. 1.12 3.10 Acid No 7 1.70 4. 00

Catalyst Weight Loss, mg "i 0.0 .9. 6

Oxidation tests carried out at 285 F. with oxygen bubbled through I oil at a rate of 6 liters per hour, with a copper-lead catalyst. Initial 0 sample is 300 cc. and an oil sample is taken every 48 hours, and 50 cc. of

' fresh'oll added at that time to simulate oil makeup procedures.

Gravity, ,fAPI

' Flash, :F; 440 Fire,.F.-, I 510 Viscosity,.SUS at 100 F. 1310 Viscosity,SUS at 210 F." 76.7 Viscosity index. 1 K V 22.3 Pour, -3:-F.' V j 1-5 Co1or,'NPA 3% Color stability (NPA) 3V2 to 4% Specific-dispersion "a; 1339": L.

Iodine-.Na V r 7 19.6 Sulfur, percent 0. 18

hydrogenation in accordancewithour invention and a I -Weclaimfl A method for the production of a lubricating oil ,frac

tion-of enhanced color, color stability and oxidation stafbilitywhich includes the steps of distilling a naphthenic base crude oil to produce a raw lube distillate fraction having a SSU viscosity at F. of from 50 to 6000 seconds, acid treating the raw distillate fraction with sul-' furic acid having a strength of from 93-98 percent by weight in amount varying from 5 to 10 pounds of acid per barrel of oil for a raw lube distillate fraction having a SSU viscosity at 100 F. of 50 seconds tofro-m 45 to 65 pounds of acid per barrel for a raw lube distillate fraction having a SSU viscosity at 100" Rot 6000 seconds, neutralizing the acid oil and Washing the oil'with water until free ofsulfonates, and then hydr'ogenating the acid- I treated raw lube distillate by passing it into contact with cobalt molybdate supported on alumina catalyst at a temperature of from 450 to 700 F., a pressure of from 400 to 700p.s.i.g. and a weight hourly space velocity of from;

5 'to 20 while the distillate is inadmixture with from 500 to 2000 standard cubic feet of hydrogen per barrel of oil and is suflicient to improve the color, color sta bility and oxidationstabilityof the oil whereby from' '5 to 30 standard cubic feet of hydrogen are reacted per barrel of oil. r

References Cited in the file of this patent UNITED STATES PATENTS 2,116,061 Dorrer May 3, 1938 2,605,213 Edwards July 29 1952 2,654,696 La Porte Oct. 6, 1953 2,673,175 Stratford et *al. Mar. 23, 1954, 2,706,167 .Harper etal. Apr. 12, 1955 2,779,711 Goretta Jan. 29, 1957 2,779,713. Cole et al. Jan. 29, 1957 OTHER REFERENCES Gurwitsch et al.: Scientific Principles of Petroleum 7 Technology (1952), pp. 410412.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No, 2,944,015 July 5, 1960 Maurice K. Rausch et al.

Column 4, lines 51: and 52, strike out "and is sufficient to improve the color, color stability and oxidation stability of the oil" insert the same after "oil" and before the period, in line 54, same column 4.

Signed and sealed this 4th day of April 1961 fit eWERNEsT w. SWIDER ARTHUR W. CROCKER ttestmg cer Acting Commissioner of Patents 

